Get help today 888-287-0471 or sign up for 24/7 text support.
American Addiction Centers National Rehabs Directory

How Long Does Fentanyl Stay in Your System?

Fentanyl Addiction, Withdrawal and Timeline

Fentanyl has been getting a lot of attention in recent years due to the significant rise in overdose deaths caused by it. Synthetic opioids, in general, are the most common cause of overdose deaths in the United States, especially those involving illicitly produced fentanyl. Over 70% of overdose deaths in 2019 involved an opioid.1 In 2017, 59% of opioid-related deaths involved fentanyl, compared to 14.3% in 2010.2

Because of its low cost, it’s added to street heroin or other drugs (cocaine, methamphetamine, and MDMA) to increase their potency, which often results in overdose deaths as most drug users snort fentanyl unaware of what they’re truly buying. This drug adulteration creates stronger opioid effects than the body is used to, so users are more likely to overdose.2

However, several factors determine the effect fentanyl can have on a user and how long its effects may last:5

  • Size, weight, and overall health
  • Whether the person is used to taking opioids
  • Whether other drugs are taken simultaneously
  • The amount
  • The strength (varies between different modes of administration, like patches, lozenges, or injection)
  • Age
  • Genetics
  • Hydration

Pharmaceutical Fentanyl

Fentanyl was originally developed as a pharmaceutical prescription drug for pain management. It was used in the treatment of cancer patients and other patients with severe chronic pain who became physically tolerant to other opioids like morphine. In its prescription form, it is known as:2

However, fentanyl became one of the most abused and diverted opioid medications due to its powerful opioid effects. Fentanyl is approximately 100 times more potent than morphine and 50 times more potent than heroin as an analgesic, which led to its widespread illicit use.3,4

You can get information and guidance about prescription drug abuse from one of the 24-hour free hotlines.

How Is Fentanyl Metabolized?

Fentanyl is metabolized in the liver, broken down into its metabolites (the main ones being norfentanyl and despropionylfentanyl, and excreted by the kidneys.6 Its inactive metabolites and less than 10% of the fentanyl itself are excreted in the urine. The fentanyl metabolites can be detected in urine, stool, and blood.7

How Long Does Fentanyl Stay in the Different Body Parts?

Even when the effects of use are only felt for a few hours, traces of the drug remain in the system for a longer period of time and can be detected through fentanyl drug testing. Detection time depends on the dose of fentanyl, duration, and frequency of use, weight, and kidney or liver function.8

  • Fentanyl hair tests can detect the drug for up to 3 months after the last use but are not commonly performed. It’s not possible to find fentanyl in hair samples shortly after use.9
  • Blood concentrations can significantly vary depending on liver function.7 Fentanyl can be detected in the blood from 5-48 hours after last use.10
  • Saliva tests are used to detect many types of drugs. However, in the case of fentanyl, saliva tests can’t consistently detect the drug itself or its metabolites.6 This applies even when it’s consumed in the lozenge form, which makes this type of testing unreliable. 7
  • Urine. You can test positive for unchanged fentanyl on a urine test for 1-3 days after the last use.9 Norfentanyl can stay present in larger quantities than fentanyl and can be detected for 48-96 hours.6

What Is the Half-Life of Fentanyl?

Fentanyl’s half-life determines how long it might stay in your system. Elimination half-life refers to the time it takes for half of the drug dose to leave the body. This can vary according to the method of use.11

If fentanyl is taken intravenously, its elimination half-life is approximately 2-4 hours. When used in the patch or lozenge form, the half-life is approximately 7-17 hours. After about 36 hours, the drug will completely leave your system.11

Is It Possible to Sweat out Fentanyl?

There are a lot of myths about the ways you can eliminate the drug from your system, like drinking lots of water, exercising, sweating it out in a sauna, or taking vitamins. However, none of these will help you get fentanyl out of your system. The only way to eliminate fentanyl from the body is to stop using it and allow your body to metabolize and excrete it naturally.6

If you need to eliminate fentanyl out of your system because you think you have taken too much of it and are afraid of dangerous effects or overdose, seek medical attention immediately. Doses as small as 2 mg can be lethal depending on one’s fentanyl tolerance, past usage, and body size. An overdose often requires the use of a medication called naloxone to temporarily block the toxic effects of an opioid drug and reverse its effects.12

Fentanyl Detection Through Drug Tests 

Like most drugs, Fentanyl can be detected through urine, saliva, hair, or blood tests. Fentanyl detection times can vary significantly depending on the type of fentanyl drug screen:

  • Hair tests. This type of test can provide information on drug use for a long period of time. Hair preserves many drugs for months after use. It can reveal the history of drug use for about 90 days. However, it can’t detect short-term use since drugs don’t incorporate into hair immediately.13
  • Urine test is good for short-term detection, particularly for drugs that get excreted fast, like cocaine, heroin, and amphetamines. A urine test can detect drugs used in the past 48-72 hours. However, it’s not effective at detecting long-term patterns of drug use.13 When trying to determine fentanyl abuse, its metabolite norfentanyl is usually tested for.6
  • Fentanyl blood testing is commonly done for diagnostic and overdose purposes, usually in hospital emergency departments in case of severely intoxicated or injured patients. Fentanyl, like most drugs, can be found in the blood for up to 48 hours.13
  • Saliva tests are performed by taking an oral fluid sample from the mouth. However, consistent detection of fentanyl or its metabolites isn’t possible at any time in saliva.6

Fentanyl tests can occasionally come up with false-positive results, even if you haven’t used the drug. The presence of other medications can occasionally trigger a fentanyl false-positive result.14

Fentanyl home drug tests are also available to help prevent overdose. Some of them test urine for the presence of fentanyl, and others detect fentanyl mixed in with other drugs.24

Are There Ways to Get Fentanyl out of the System?

The only reliable and therefore the best way to get fentanyl out of your system is to stop using it and wait for your liver to metabolize it, so your body can eliminate it naturally. If you’re worried that you, or someone else, might have a dangerous amount of fentanyl in the system, call 911 or Poison Control to receive immediate medical attention.15

Fentanyl can have dangerous cross-reactions with other drugs, sedatives, benzodiazepines (like Xanax, Ativan, Klonopin), and alcohol. Taking these substances simultaneously can amplify the depressing effects of fentanyl on the central nervous system.16

Medical personnel can administer Naloxone in case of an opioid drug overdose. A fentanyl overdose can lead to coma and death, so pay attention to these symptoms:17

  • Slowed breathing.
  • Bluish lips and complexion.
  • Chest pain.
  • Passing out.
  • Seizure.

Is It Possible to Stop Fentanyl Use Cold Turkey?

Fentanyl is a highly addictive opioid drug because of its potency. Even people taking prescription fentanyl can develop dependence, characterized by withdrawal symptoms when the use is stopped. Fentanyl withdrawal symptoms can be extremely uncomfortable which makes it hard for many people to stop taking it.2

Withdrawal symptoms can begin as early as a few hours after use, or within 12 hours after the last dose. They can last for up to a week. Symptoms include:18

  • Muscle and bone pain.
  • Irritability.
  • Insomnia.
  • Loss of appetite.
  • Diarrhea, nausea, vomiting.
  • Cold flashes alternating with bouts of flushing and excessive sweating.
  • Uncontrollable leg movements.
  • Severe cravings.
  • Increased heart rate and blood pressure.
  • General weakness.
  • Depression.

If fentanyl detox for a drug test is your concern, the most responsible solution would be seeking out same-day professional help to safely clear fentanyl out of your system and manage any withdrawal symptoms.

How to Get Help for Fentanyl Addiction

Since trying to quit fentanyl use cold turkey on your own can be extremely uncomfortable and dangerous, most people are unable to do it without professional help and medically assisted detoxification.18

Just like with other opioid drugs, medication-assisted fentanyl treatment in combination with counseling and behavioral therapies has high rates of success in treating people with a fentanyl addiction. Medications used (buprenorphine and methadone) work by binding to the same opioid receptors in the brain as fentanyl, reducing cravings and withdrawal symptoms. Behavioral treatment approaches help patients modify their attitudes and behaviors to adopt healthy coping skills.2

As one of the leading addiction treatment providers, American Addiction Centers offers a full spectrum of care across many locations nationwide:

Our hotline advisors can help you get accurate information about substance abuse. Additionally, one of the admissions navigators can verify your insurance coverage or explain the benefits of private pay options. They can also guide you through the steps of the intake process and the initial evaluation to determine the best type of treatment.

You can also call your insurance provider (their number is provided at the back of your health insurance card) and ask them about rehab coverage and potential additional costs of addiction treatment. Our alcohol and drug addiction hotlines are also available to provide you with guidance. Finally, you can fill out the online form on our website to check your benefits and payment options

Frequently Asked Questions

How Long Is the Fentanyl High?

This depends on many factors, like dosage, method of use (patches, lozenges, injection), previous experience with opioid use, overall health, and age. When injected, fentanyl has faster redistribution and a 4-hour half-life, so the duration of its “high” is shorter (30-40 min).19

Its effects may include:4

  • Euphoria, relaxation, sedation.
  • Relief from pain.
  • Nausea and/or vomiting.
  • Reduced appetite.
  • Drowsiness.
  • Weakness, fatigue, dizziness.
  • Headache.
  • Slurred speech.
  • Slow pulse and lower blood pressure.

How Long Do the Effects of Fentanyl Last?

Fentanyl activity might increase or decrease according to variations in the gastrointestinal tract and the liver. Fentanyl metabolism and blood concentrations can vary depending on liver function.5

Fentanyl affects everyone differently, based on:5

  • Body size, weight, and health.
  • Whether they’re used to taking it.
  • Whether fentanyl and alcohol or other drugs are taken simultaneously.
  • Amount and strength of the drug (varies between different forms: patches, lozenges, injection).

How Long Does Fentanyl Take to Kick in?

This depends on how it’s taken:20 

  • Fentanyl patches can take up to 2 days to start working but they last longer.
  • When fentanyl is injected, peak effects are felt within minutes and last 30-60 minutes.
  • Oral use (tablets, lozenges) has two phases. The first one will happen within a few minutes, while absorption through the intestinal tract will be occurring over the next 2 hours. 
  • Nasal sprays are also fast-acting. They take 15-30 minutes to work and 4-6 hours to wear off.

How Long Does Fentanyl Stay in Your Urine?

Urine detection time for fentanyl is about 24-72 hours after last use, while norfentanyl, a metabolite created in the process of breaking down the drug, can be detected for up to 96 hours.6

How Long Does the Fentanyl Patch Stay in Your System?

When a patch is removed, fentanyl continues to be absorbed into the circulation from the skin depot of the drug. The terminal fentanyl half-life for the patch is 13-25 hours.21

Can Fentanyl Cause Bipolar Disorder?

A lot of people with bipolar disorder, especially when untreated, abuse drugs as a way to self-medicate and relieve the symptoms caused by their condition. Fentanyl might seem to ease the symptoms of manic and depressive episodes at first, but it may also exacerbate them, make them more frequent, or trigger episodes.22

However, the high prevalence of comorbidity between SUDs and other mental illnesses doesn’t necessarily mean that one caused the other. Many areas of the brain are affected by both SUDs and other mental health disorders. Most drugs can cause mental health issues, but fentanyl is currently of particular concern. It’s very potent and acts quickly, so it poses a bigger risk of causing addiction.23 

Can Fentanyl Cause Anxiety?

Around 43% of people in treatment for nonmedical use of prescription painkillers suffer from mental health disorders, particularly depression and anxiety. One of the reasons behind this is the attempt to relieve anxiety symptoms by using drugs. People who do this usually end up worsening their condition, which is particularly evident when they experience withdrawal symptoms, which can often be much worse than the initial anxiety symptoms they were trying to avoid.22

Fentanyl use can cause changes in some of the same brain areas that are disrupted in other mental disorders, such as anxiety. Drug use that precedes the first symptoms of anxiety, or any other mental health disorder, may produce changes in brain structure and function that trigger an underlying predisposition to that particular mental illness.23


  1. Centers for Disease Contron and Prevention. (2021). Understanding the Epidemic.
  2. National Institute on Drug Abuse. (2021). Fentanyl DrugFacts.
  3. Drug Enforcement Administration. (2017). Drugs of Abuse.
  4. United States Drug Enforcement Administration. Fentanyl.
  5. Feierman DE, Lasker JM (1996). Metabolism of fentanyl, a synthetic opioid analgesic, by human liver microsomes. Role of CYP3A4. Drug Metab Dispos, 24(9), 932-9.
  6. Silverstein J.H., Rieders, M.F., McMullin, M., Schulman, S., Zahl, K. (1993). An analysis of the duration of fentanyl and its metabolites in urine and saliva. Anesthesia & Analgesia, 76(3), 618-21.
  7. Wilde, M., Pichini, S., Pacifici, R., Tagliabracci, A., Busardò. F. P., Auwärter V., Solimini, R. (2019). Metabolic Pathways and Potencies of New Fentanyl Analogs. Frontiers in Pharmacology 10.
  8. Moeller, K., Kissack, J., Atayee, R., and Lee, K. (2017). Clinical Interpretation of Urine Drug Tests: What Clinicians Need to Know About Urine Drug Screens. Mayo Clinic Proceedings.
  9. Palamar JJ, Salomone A, Bigiarini R, Vincenti M, Acosta P, Tofighi B. Testing hair for fentanyl exposure: a method to inform harm reduction behavior among individuals who use heroin. Am J Drug Alcohol Abuse. 2019;45(1):90-96.
  10. Schwartz J.G., Garriott J.C., Somerset J.S., Igler E.J., Rodriguez R., Orr M.D. (1994). Measurements of fentanyl and sufentanil in blood and urine after surgical application. Implication in detection of abuse. American Journal of Forensic Medicine and Pathology, 15(3), 236-41.
  11. Kharasch E. D. (2015). Opioid Half-lives and Hemlines: The Long and Short of Fashion. Anesthesiology, 122(5), 969–970.
  12. United States Drug Enforcement Administration. (2020). Alarming spike in fentanyl-related overdose deaths leads officials to issue public warning.
  13. The University of Arizona. (2018). Biological Tests.
  14. Zacher, J.L., Givone, D.M. (2004). False-positive urine opiate screening associated with fluoroquinolone use. Ann Pharmacother. 38(9),1525-8.
  15. Centers for Disease Contron and Prevention. (2011). Fentanyl: Incapacitating Agent.
  16. Centers for Disease Control and Prevention. (2020). Fentanyl.
  17. U.S. Department of Health and Human Services. Medline Plus. (2020). Fentanyl Transdermal Patch.
  18. Brands B, Sproule B, & Marshman J. (1998). Drugs & Drug Abuse. 3rd ed. Ontario: Addiction Research Foundation.
  19. ScienceDirect. (2021). Fentanyl.
  20. Sullivan, K., Cammarano, W., Wiener-Kronish, J. (2010). Analgesics, Tranquilizers, and Sedatives. Cardiac Intensive Care (Second Edition)
  21. Grond S, Radbruch L, Lehmann KA. (2000). Clinical pharmacokinetics of transdermal opioids: focus on transdermal fentanyl. Clin Pharmacokinet 38(1), 59-89.
  22. National Institute on Drug Abuse. (2021). Part 1: The Connection Between Substance Use Disorders and Mental Illness.
  23. National Institute on Drug Abuse. (2021). Why is there comorbidity between substance use disorders and mental illnesses?.
  24. (2018). Rapid Self-Testing to Prevent Fentanyl Overdose Among Young People Who Use Drugs (RAPiDS2)
Was this page helpful?
Thank you for your feedback.

American Addiction Centers (AAC) is committed to delivering original, truthful, accurate, unbiased, and medically current information. We strive to create content that is clear, concise, and easy to understand.

Read our full editorial policy

While we are unable to respond to your feedback directly, we'll use this information to improve our online help.